#define _CRT_SECURE_NO_WARNINGS 1
class Solution {
public:
    int longestPalindromeSubseq(string s) {
        int n = s.size(), ret = 0;
        vector<vector<int>> dp(n, vector<int>(n));
        for (int i = n - 1; i >= 0; i--)
        {
            for (int j = i; j < n; j++)
            {
                if (s[i] == s[j] && i == j) dp[i][j] = 1;
                else if (s[i] == s[j]) dp[i][j] = dp[i + 1][j - 1] + 2;
                else dp[i][j] = max(dp[i + 1][j], dp[i][j - 1]);
            }
        }
        return dp[0][n - 1];
    }
};